A researcher from the University of California, Santa Barbara, David Cleveland, set out to find exactly what sorts of environmental effects gardening can have. And his findings, published in the journal Landscape and Urban Planning, are bold: For every kilogram of vegetables you grow yourself, you’re reducing greenhouse gas emissions by 2 kilograms, compared to buying from the store.

Of course, the findings get more complicated. The density of vegetables planted matters, because the greenhouse gas emissions were calculated by square meter. The use of grey water—not-dirty-but-not-clean-either water, like reused water from the shower or sink—can also have a big effect on the environmental output, too.